Better Gas Mileage with 87

[Jeff2017]

I drive about 7500 miles a years. 93 octane is .37 more a gallon at Costco. I average 18MPG. So I burn 413 gallons a years which comes to $153 extra for 93. I am not adjusting for any additional mileage I might get with 93 octane.

 

[Jordan Arthur]

I drive about 7500 miles a years. 93 octane is .37 more a gallon at Costco. I average 18MPG. So I burn 413 gallons a years which comes to $153 extra for 93. I am not adjusting for any additional mileage I might get with 93 octane.

So this isn't ur DD? 7500 miles is insanely low

 

[Jeff2017]

So this isn't ur DD? 7500 miles is insanely low

It is my DD. My office is only 7 miles from home. I haven't even put 16k miles on it yet.

 

[wkienzle]

I've switched back and forth between 87 and 93 many times. I've heard most people justify the cost which here is about .60/gal difference by the increase in gas mileage they got with 93 but it's been the opposite for me. I try to drive the same with both and maybe but rarely I romp it a bit more with 93 but I don't exactly baby the throttle with 87.

Has anyone else gotten better mileage with 87? I know the 87 vs 93 debate has been beat to death but I just can't justify the cost difference at this point with the slightly better performance you get with 93 which to be honest I can't notice either. I rarely use sport mode but when I do and having a PP car it's night and day almost in terms of acceleration but that's the same with both octanes.

Is it truly better for our cars to run 93 for longevity and reliability?

I also noticed that the gas mileage is somewhat better with 87 compared to 93 on my '90 SHO. This happens when I drive on the expressway. I believe premium fuel would make for a better driving experience when around town with a lot of starts and stops or when I want more performance; if I need to lay into it a lot, performance is better with 93 octane. When I am on the highway cruising at a constant speed, performance is less of a factor.

 

[JAMES'12SHO]

I am in Colorado so we have 85 octane. At 8,000 ft elevation on 85 octane the car can maintain 130mph at 24 mpg on a flat road. At 3500 ft the car cannot go 100 mph without pinging. At 6000 ft on 85 octane the car doesn’t like wot but cruising around is just fine. The more you ask of your car the better fuel and higher octane you need. Not sure why people are against ethanol though as I have far better performance on 20-24% ethanol fuel than on 91 octane (highest we can get in these here parts)

 

[Eric Morris]

Man, you guys must have magic SHOs. One guy is claiming he gets 30+ MPG combined and another claims his can pull down 24 MPG at 130 MPH.

Sounds like anecdotal stories to me. Without some data to back it up- I'm calling BS on both claims.

I've tracked my mileage since I've owned it, every fill up, both gallons and miles. Driving nearly all highway (generally at less than 70 MPH) and basically hyper-mileing it, I've seen anywhere from 20 MPG in the dead of winter to 26 MPG in the fall/spring. I'm at 23 MPG overall now and have the data to back it up.

 

[SM105K]

That is weird......


And I was mistaken.....it is 30.6 combined. That last .6 miles cost me 13K.

 

[wkienzle]

I am in Colorado so we have 85 octane. At 8,000 ft elevation on 85 octane the car can maintain 130mph at 24 mpg on a flat road. At 3500 ft the car cannot go 100 mph without pinging. At 6000 ft on 85 octane the car doesn’t like wot but cruising around is just fine. The more you ask of your car the better fuel and higher octane you need. Not sure why people are against ethanol though as I have far better performance on 20-24% ethanol fuel than on 91 octane (highest we can get in these here parts)

That is interesting. How are you getting to 20-24% ethanol? Are you filling up the last 1/4 of the tank or so with E-85? E-85 is considered 105 octane. At 25% ethanol and 75% 85 octane, if I did my math correctly, you would have a tankful of 90 octane. If you start with 87 octane gas, the calculated result of 25% E-85 is 91.5 octane

 

[Johnbigdog]

Man, you guys must have magic SHOs. One guy is claiming he gets 30+ MPG combined and another claims his can pull down 24 MPG at 130 MPH.

Sounds like anecdotal stories to me. Without some data to back it up- I'm calling BS on both claims.

I've tracked my mileage since I've owned it, every fill up, both gallons and miles. Driving nearly all highway (generally at less than 70 MPH) and basically hyper-mileing it, I've seen anywhere from 20 MPG in the dead of winter to 26 MPG in the fall/spring. I'm at 23 MPG overall now and have the data to back it up.

I think tires play a roll. (Pun wasn't intended) with my winters I cant get above 23 on my 16 with performance package. My car is well broken in.

On a long trip with my summer tires dropping my speed to 65-70 I have seen 25 or a shy better. This in on 91+. It seems to me ethanol free gets better mpg.

 

[JAMES'12SHO]

That is interesting. How are you getting to 20-24% ethanol? Are you filling up the last 1/4 of the tank or so with E-85? E-85 is considered 105 octane. At 25% ethanol and 75% 85 octane, if I did my math correctly, you would have a tankful of 90 octane. If you start with 87 octane gas, the calculated result of 25% E-85 is 91.5 octane

Yes. But you add E85 first to ensure you have the right balllance. I run straight 91 ever 4th tank to help reduce getting to much ethanol.

 

[JAMES'12SHO]

I think tires play a roll. (Pun wasn't intended) with my winters I cant get above 23 on my 16 with performance package. My car is well broken in.

On a long trip with my summer tires dropping my speed to 65-70 I have seen 25 or a shy better. This in on 91+. It seems to me ethanol free gets better mpg.

I did have summer tires when I averaged 24 mpg at 130 mph. It also wasn’t tuned. I can get 19 mpg in town with ethanol rich fuel and 20 without. I prefer power to mileage though

 

[6500rpm]

Volumetric efficiency of ethanol is lower than gasoline, so it only seems to make sense that the higher the E content, the lower the gas mileage should be. I can't see any increase in spark advance or boost making up for it?

 

[SM105K]

Man, you guys must have magic SHOs. One guy is claiming he gets 30+ MPG combined and another claims his can pull down 24 MPG at 130 MPH.

Sounds like anecdotal stories to me. Without some data to back it up- I'm calling BS on both claims.

I've tracked my mileage since I've owned it, every fill up, both gallons and miles. Driving nearly all highway (generally at less than 70 MPH) and basically hyper-mileing it, I've seen anywhere from 20 MPG in the dead of winter to 26 MPG in the fall/spring. I'm at 23 MPG overall now and have the data to back it up.

Sounds like you are doing it wrong.....I love my magic SHO.

 

[wkienzle]

Sounds like you are doing it wrong.....I love my magic SHO.

LOL. I thought all SHOs were magic. Too bad new ones will soon do a disappearing act.

 

[SM105K]

LOL. I thought all SHOs were magic. Too bad new ones will soon do a disappearing act.

They already have. Last one has already been built and shipped.

 

[jman1200]

I average 13 l/100 km (~18 mpg)... and no, my parking brake is not on.

 

[SM105K]

I average 13 l/100 km (~18 mpg)... and no, my parking brake is not on.

My 30 mpg was on the road trip home after I bought her. Car was bone stock, on 87 octane, averaging 75 mph, and my tires were set at 42 psi. It did average over 30 mpg for 330 miles. My car while stock was averaging right at 25 mpg combined when I was DD'ing it 500 miles a week. 400 miles of which were mainly freeway miles.

Once I tuned the car it was averaging right at 22 mpg even with the E30 tune. Once again alot of highway miles.

Since then, I bought the Focus ST and stock it was getting 28 mpg combined. Since I tuned it, MPG's have gone up roughly 2.5 mpg combined to 30.5 mpg.

Since I have the ST, The SHO now gets driven sparingly and far more aggressive. Still on E30 and I am willing to bet that MPG will settle in the 15 mpg range. I took the picture below last night.



As you can see. I have roughly put 20k miles on my SHO in 11 months. Two months it was down while I was getting the trans replaced, and for the past three months it has been driven less then two thousand miles.

 

[ridered74]

On my old SHO (2011), I averaged 31 mpg driving from Ohio to New York City. It was around 485 miles if I remember correctly. I was driving the entire time trying to get the best mileage I could, and went 55-60 mph a good part of the way. It only took about half a mile of driving on regular roads in new york to have the computer drop it down to 28.5 mpg for the tank average, but when I pulled into a gas station and filled it up and did the math manually, the number I came up with was within a tenth of a gallon of what the computer said, so I don't doubt that the 31 was accurate before I hit the city.

I can't even come close to that on my 2015, I think the closest I have come is 26 or 27 mpg. The trip to New York was before I put downpipes on, and my new car has those pipes now. I tracked every drop of gas and mileage on that car the first three years I owned it, I had averaged 23 mpg over the first year, but after adding downpipes it dropped to about 21.5 mpg over the next two years doing mostly the same type of driving.

 

[Jordan Arthur]

Man, you guys must have magic SHOs. One guy is claiming he gets 30+ MPG combined and another claims his can pull down 24 MPG at 130 MPH.

Sounds like anecdotal stories to me. Without some data to back it up- I'm calling BS on both claims.

I've tracked my mileage since I've owned it, every fill up, both gallons and miles. Driving nearly all highway (generally at less than 70 MPH) and basically hyper-mileing it, I've seen anywhere from 20 MPG in the dead of winter to 26 MPG in the fall/spring. I'm at 23 MPG overall now and have the data to back it up.

I'm with this guy, yall sure you on the right forum? Does your badges say SEL instead of SHO?? lol...but seriously, I get anywhere from 18.1-20ish at best on a tank. It's mostly city commute with a few stretches of interstate for 5 or less miles and lots of stop lights, so yeah. Even on my road trips of all interstate, best I've seen is 24ish and again the octane made no difference then either per my experimentation.

 

[SHOdded]

Just curious, have you ever done a KAM reset, Jordan? Wondering if the PCM relearns your driving conditions, will it make a difference afterwards.

I think factory tune differences in economy are fairly mild anyway, they are tuning more for hp/tq (which also by mod standards is mild).